Electrical service furnishes 240 volts single phase alternating current to virtually all customers of power utilities in the United States. The relative inexpensiveness and widespread availability of such service has caused manufacturers to equip their machinery to utilize such current in power requirements up to about three horsepower, and also to manufacture products which utilize such current. The motors most commonly used with alternating current are characterized by near constant operating speed and low starting torque when compared to motors which utilize polyphase or direct current. Where a greater range of speed and torque control is required than is possible with single phase alternating current motors, motor driven generators or rectifiers may be used to supply direct current to a machine drive motor from single phase alternating current service.
The method and means of this invention increases the range of continuously variable tool speed and torque control from that heretofore available to operate machine tools from single phase alternating current by additively coupling interactive machine operator manual control of mechanical regulation of speed and torque to that of electrical control using direct current motor drive, to effect reduction or elimination of machine down time needed for performing a series of machine operations requiring differing tool speeds and torques.